JPS59169993A - Synthesis of diamond - Google Patents

Abstract

PURPOSE:In synthesizing a diamond by ultra-high pressure and high temperature method using a seed grain of diamond, solvent metal and carbon, to synthesize a diamond having a low content of impurities and good shape of crystal grain, by coating the surface of the seed grain of diamond with the solvent metal and a nonsolvent metal. CONSTITUTION:The surface of the seed grain 11 of diamond having about 30 particle diameter to be used for synthesis of diamond is coated with the solvent metal 12 such as Fe, Co, Ni, Cr, Ta, etc. by plating, vacuum metallizing, sputtering, flame spraying, and other methods to form a film with 0.1-2mu thickness. The surface is then covered with the nonsolvent metal 13 such as Cu, Ag, Pb, Sn, Si, Al, etc. to give a film of 5-100mu thickness, so that the seed diamond 14 is prepared. 7pts.wt. seed diamond is blended with 100pts.wt. graphite as a carbon raw material and 100pts.wt. powder of solvent metal such as Ni, etc., reacted at 1,450 deg.C at 58,000 atmospheric pressure, so that a high-quality diamond free from crystal defect can be synthesized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for synthesizing diamonds, and more specifically, diamonds with low impurities and good crystal grain shape? 0 Regarding synthesis methods Diamond is primarily used for polishing, grinding, cutting, etc., but in this case, the particle shape of the diamond is a problem.
The abrasive grains classified as K are so-called euhedral grains having a polyhedral grain shape, and α are large grains.

In order to produce large, high-quality diamond crystals, it is necessary to completely suppress and reduce the generation of diamond crystal nuclei, and to gradually crystallize the diamond crystals in the stable diamond region near the phase equilibrium with those few nuclei. The C-1 yuzu method is used when synthesizing large and L diamonds by limiting the size of the nucleus to O)F<, which needs to be grown. Singletons used in this method include diamond grains, z'f, or those made of fertilized metal, but messengers are usually used. In the above method, even if you reduce the number of seeds added to the reactant and completely limit the number of nuclei in the river, you will not be able to obtain good quality diamond crystals (if diamond crystals are grown in a highly supersaturated region of 0 degrees). No crystals were obtained, the shape of the crystals was poor, and impurity n
There will also be more.

Therefore, as shown in the figure, diamond stability region 1
The entire crystal must grow under the conditions of point A within the phase equilibrium line 2 and near the phase equilibrium line 2.

By the way, in order to obtain the conditions for the reaction P @ point A in Fig. 1, the pressure of the reactant is made from point B to the point The, and then the temperature is raised to obtain the conditions for point A. In case of stiffness, the wetness is fully increased and then the pressure is fully raised by 2f, which is often a tough decision. Therefore A
In order to obtain the point condition, the reactant must Jfn the part D, which is the diamond stable region away from the phase equilibrium line 2. Since the seeds in the above reactant are simply covered with the solvent metal, the carbon dissolves in the solvent gold mK, and diamonds grow on the seed surface. , after that, there is a disadvantage that a good crystal cannot be obtained even under the A point condition.

In view of the above circumstances, the entire purpose of the present invention is to provide a diamond synthesis method that suppresses the growth of crystals on seeds during the process of creating conditions near the phase equilibrium line between all diamond and graphite as reactants. , the gist of which is a diamond synthesis method in which the entire reactant consisting of non-diamond carbon, a solvent metal, and a seed is maintained at high temperature and pressure. This is a method of synthesizing diamonds, which is characterized by having a complete circle coated with metal.

The present invention will be explained in detail below.

As shown in FIG. 2, the interlocks used in the present invention are made by corrugating the surface of a diamond particle 11 with a solvent metal 12, and roughly corrugating the entire surface with a non-solvent metal 13. 4 of Kabanari above! R element 14 is formed with a reactant by non-diamond carbon (hereinafter referred to as raw carbon) and R8 medium metal and loaded into an ultra-high pressure reactor to form diamond 2 mixture D.
I Sur.

Diamond particles 11t-Mffl”j of the above Yuzu 14
Examples of solvent gold 412 include F'e, Co, +Ni, etc., and ordinary diamond metals such as Cr, Ta, etc.
A series of solvents commonly used are used. Its thickness is θ
/-U□ or appropriate. The non-solvent metals 18 on the outside of fl are Cu, Ag, Pb, and Sn.

Z-n, Si, ACGe, W, Mo, and Ti-5 are used, and the thickness is 3 to 100 μm per i1M. Roughly speaking, it is desirable that the diamond particles 11 have an EfL of 3θμ or more.

Diamond particle 11'? ! : To coat with the solvent metal 12 and the non-solvent metal 18, the following methods are commonly used for coating ceramics: electroless, vacuum evaporation, compound gas deposition, liquid decomposition, svantaling, Ion blasting, thermal spraying, etc. are used depending on the a-term of the metal.

diamond? When synthesizing, the reactant containing the 4H molecules 14 reaches the conditions of point A from point B to point C, as shown in Figure 1, as in the conventional synthesis method. In the process, the entire D section is passed through. However, since the outside of the seed 14 is covered with the non-solvent metal 18, as shown in FIG. Even if the raw material carbon 16 is present dissolved in the constituent solvent metal 15, it does not come into contact with the diamond particles 1, and no crystals that serve as diamond particle ILTh nuclei grow. However, over time, diamond particles 1
The solvent metal (1) 2 and the non-solvent metal (18) on the surface of diamond particle (1) are eroded together, raw carbon is dissolved therein, and crystal formation and scratches begin on the surface of diamond particle (11).

However, at the time of warping, the reactants are under the conditions of the GJA point, and diamond crystal growth occurs slowly, resulting in the synthesis of high-quality diamond.

f, solvent gold 12 covering diamond particles 11
In the process of reaching point A, diamond 110
Slightly dissolve the whole surface and smooth out the unevenness of the blood.
This improves the shape of the diamond that grows as a center. Therefore, the above method is particularly suitable for a case where all 41 diamond particles are composed of diamond particles having a rough shape.

Next, the present invention shown in Example 2 will be explained in detail.

〔Example〕

Approximately /, using 20μ diamond particle sound, first C')
No 13 on J side. Plating is performed to a thickness of Ni kO,jμ using the deplating method. This was then electrolyzed with sulfuric acid (M) solution, and the copper was coated with a thickness of 2θμ.

This seed 77@i company uses graphite lθ0 heavy U as raw material carbon.
Part 5: Ni powder was used as a melted metal.The pressure and temperature were increased as shown in the diagram, and two synthesis operations were carried out under the conditions of point A at 5θ°C and 55,000 atm.

The resulting diamond had a grain size of approximately toθμ, a monog-hedral shape, and was of good quality with no crystal defects.

[Brief explanation of drawings]

Figure 1 is a diagram showing the entire process P-T diagram using reactants as conditions for Di-N-Mondo synthesis, Figure 2 is a diagram of 7-sako,
FIG. 3 shows that the entire IM region of the seed is surrounded by graphite dissolved in a bath of 18 metals. 11...diamond particles, 12...
Bath metal, 18...Non-solvent gold, 14...
···seed. Dekinuto Showa Kaiko Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] Reactant consisting of non-diamond carbon, solvent metal and f, J atoms? In the diamond synthesis method that maintains the diamond particles at high temperature and high pressure, the diamond particles are all-solvent gold J<
A method for synthesizing diamond, characterized in that the diamond is thinly coated with 4, and the entire outer layer is coated with a non-solvent metal.